#include <bits/stdc++.h>
#include <atcoder/all>
#include <boost/polygon/point_data.hpp>
#include <boost/polygon/voronoi.hpp>
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define all(x) begin(x),end(x)
#define sz(x) (int)(x).size()
using namespace std;
using namespace atcoder;
using ll=long long;
using ld=long double;
using vll=vector<ll>;
using vvll=vector<vll>;
using vi=vector<int>;
using vvi=vector<vi>;
using pll=pair<ll,ll>;
using pi=pair<int,int>;

// using mint=modint998244353;

// using BoostPoint=boost::polygon::point_data<int>;
// using Voronoi=boost::polygon::voronoi_diagram<double>;


int main()
{
  	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	int N,s=0;
	cin>>N;
	vi w(N);
	rep(i,0,N)cin>>w[i],s+=w[i];
	if(s%2==1){
		cout<<"impossible\n";
		return 0;
	}
	int t=s/2;
	vector<bool>dp(t+1,false);
	dp[0]=true;
	rep(i,0,N){
		rrep(j,0,t+1){
			if(j-w[i]>=0&&dp[j-w[i]])dp[j]=true;
		}
	}
	if(dp[t])cout<<"possible\n";
	else cout<<"impossible\n";

}